An organic light-emitting device includes: an anode; a cathode; and a thin film containing a fluorescent organic compound or a phosphorescent organic compound, the thin film being interposed between the anode and the cathode. An electron and a hole are injected from the respective electrodes to the thin film.
Further, the organic light-emitting device generates an exciton of the fluorescent organic compound or of the phosphorescent organic compound. The device utilizes light to be radiated when the exciton returns to its ground state.
Recent progress in an organic light-emitting device is remarkable. There are characteristics capable of producing a thin, lightweight organic light-emitting device having high luminance at a low applied voltage, various emission wavelengths and high-speed responsiveness. Therefore, these characteristics suggest that the light emitting device may be used in a wide variety of applications.
However, the conventional organic light-emitting device requires optical output with higher luminance or higher conversion efficiency. In addition, the organic light-emitting device still involves many problems in terms of durability such as a change with elapse of time due to long-term use and deterioration due to, for example, an atmospheric gas containing oxygen or humidity.
Further, when it is attempted that the device is applied to a full-color display and the like, blue light, green light, and red light must be emitted at a good color purity. However, problems concerning the emission have not been sufficiently solved yet.
In addition, the examples of a material and an organic light-emitting device using a fluorene compound are disclosed in Japanese Patent Application Laid-Open Nos. H11-288783, H11-185960, H11-204262, 2002-154993, 2004-043349, and 2005-239650. However, the devices disclosed in those applications have a low emission efficiency and an insufficient durable lifetime. In addition, some of the applications describe nothing about a durable lifetime.